The Fanconi anemia complementation group (FANC) currently includes FANCA, FANCB, FANCC, FANCD1 (also called BRCA2), FANCD2, FANCE, FANCF, FANCG, FANCI, FANCJ (also called BRIP1), FANCL, FANCM and FANCN (also called PALB2). The previously defined group FANCH is the same as FANCA. Fanconi anemia is a genetically heterogeneous recessive disorder characterized by cytogenetic instability, hypersensitivity to DNA crosslinking agents, increased chromosomal breakage, and defective DNA repair. The members of the Fanconi anemia complementation group do not share sequence similarity; they are related by their assembly into a common nuclear protein complex. This gene encodes the protein for complementation group F. [provided by RefSeq, Jul 2008]
Ramanagoudr-Bhojappa R, Carrington B, Ramaswami M, et al. Multiplexed CRISPR/Cas9-mediated knockout of 19 Fanconi anemia pathway genes in zebrafish revealed their roles in growth, sexual development and fertility. PLoS Genet. 2018; 14(12):e1007821 [PubMed] Free Access to Full ArticleRelated Publications
Fanconi Anemia (FA) is a genomic instability syndrome resulting in aplastic anemia, developmental abnormalities, and predisposition to hematological and other solid organ malignancies. Mutations in genes that encode proteins of the FA pathway fail to orchestrate the repair of DNA damage caused by DNA interstrand crosslinks. Zebrafish harbor homologs for nearly all known FA genes. We used multiplexed CRISPR/Cas9-mediated mutagenesis to generate loss-of-function mutants for 17 FA genes: fanca, fancb, fancc, fancd1/brca2, fancd2, fance, fancf, fancg, fanci, fancj/brip1, fancl, fancm, fancn/palb2, fanco/rad51c, fancp/slx4, fancq/ercc4, fanct/ube2t, and two genes encoding FA-associated proteins: faap100 and faap24. We selected two indel mutations predicted to cause premature truncations for all but two of the genes, and a total of 36 mutant lines were generated for 19 genes. Generating two independent mutant lines for each gene was important to validate their phenotypic consequences. RT-PCR from homozygous mutant fish confirmed the presence of transcripts with indels in all genes. Interestingly, 4 of the indel mutations led to aberrant splicing, which may produce a different protein than predicted from the genomic sequence. Analysis of RNA is thus critical in proper evaluation of the consequences of the mutations introduced in zebrafish genome. We used fluorescent reporter assay, and western blots to confirm loss-of-function for several mutants. Additionally, we developed a DEB treatment assay by evaluating morphological changes in embryos and confirmed that homozygous mutants from all the FA genes that could be tested (11/17), displayed hypersensitivity and thus were indeed null alleles. Our multiplexing strategy helped us to evaluate 11 multiple gene knockout combinations without additional breeding. Homozygous zebrafish for all 19 single and 11 multi-gene knockouts were adult viable, indicating FA genes in zebrafish are generally not essential for early development. None of the mutant fish displayed gross developmental abnormalities except for fancp-/- fish, which were significantly smaller in length than their wildtype clutch mates. Complete female-to-male sex reversal was observed in knockouts for 12/17 FA genes, while partial sex reversal was seen for the other five gene knockouts. All adult females were fertile, and among the adult males, all were fertile except for the fancd1 mutants and one of the fancj mutants. We report here generation and characterization of zebrafish knockout mutants for 17 FA disease-causing genes, providing an integral resource for understanding the pathophysiology associated with the disrupted FA pathway.
Zhang X, Shi Y, Song L, et al. Identification of mutations in patients with acquired pure red cell aplasia. Acta Biochim Biophys Sin (Shanghai). 2018; 50(7):685-692 [PubMed] Related Publications
Idiopathic acquired pure red cell aplasia (PRCA) is a rare, autoimmune-related disease. This study aimed to describe the previously unidentified DNA alterations associated with PRCA. Here, next generation sequencing using a panel containing 295 critical genes was applied to detect potentially pathogenic mutations in four patients with PRCA. A total of 529 mutations were identified and further classified into three categories, namely, uncertain (n = 25), likely benign (n = 20) and benign (n = 484) mutations, based on the American College of Medical Genetics and Genomics (ACMG) 2015 guidelines and ClinVar database. The spatial proximity between two loci of the uncertain or benign mutations was evaluated using Hi-C datasets of KBM7 and K562 cell lines, respectively. Significant spatial proximity was observed in uncertain mutation pairs compared with benign mutation pairs. In addition, 17 variants were eventually identified after excluding those with mutant frequencies >0.001, including 7 newly identified variants. FANCF and LRP1B mutations existed twice in patients. FANCF and LRP1B mutations were likely to affect protein stability based on prediction analysis. Taken together, our data may provide valuable information about PRCA. FANCF and LRP1B mutations may be associated with acquired PRCA.
Kessous R, Octeau D, Klein K, et al. Distinct homologous recombination gene expression profiles after neoadjuvant chemotherapy associated with clinical outcome in patients with ovarian cancer. Gynecol Oncol. 2018; 148(3):553-558 [PubMed] Related Publications
OBJECTIVE: The expression of homologous recombination (HR) genes in high grade ovarian cancer (HGOC) samples from debulking surgeries were correlated to outcomes in patients selected for chemotherapy treatment regimens. STUDY DESIGN: RNA was extracted from 96 fresh frozen tumor samples from debulking surgeries from chemotherapy naïve patients with HGOC (primary derived surgeries (PDS), n = 55) or following neoadjuvant chemotherapy treatment (NACT), n = 41). The samples were selected for high tumor content by a gynecological pathologist, and cancer cell content was further confirmed using a percent tumor content covariate, and mutation score covariate analysis. Gene expression analysis was performed using a tailored NanoString-based Pancancer Pathway Panel. Cox proportional hazard regression models were used to assess the associations between the expression of 19 HR genes and survival. RESULTS: In the PDS group, over-expression of six HR genes (C11orf30, NBN, FANCF, FANCC, FANCB, RAD50) was associated with improved outcome, in contrast to the NACT group where four HR genes (BRCA2, TP53, FANCB, RAD51) were associated with worse outcome. With the adding extent of debulking as a covariate, three HR genes (NBN, FANCF, RAD50), and only one HR gene (RAD51) remained significantly associated with survival in PDS and NACT groups, respectively. CONCLUSION: Distinct HR expression profiles define subgroups associated with overall outcome in patients that are exposed to neoadjuvant chemotherapy and not only chemotherapy-naïve patients.
Approximately 5-10% of all pancreatic cancer patients carry a predisposing mutation in a known susceptibility gene. Since >90% of patients present with late stage disease, it is crucial to identify high risk individuals who may be amenable to early detection or other prevention. To explore the spectrum of hereditary pancreatic cancer susceptibility, we evaluated germline DNA from pancreatic cancer participants (n = 53) from a large hereditary cancer registry. For those without a known predisposition mutation gene (n = 49), germline next generation sequencing was completed using targeted capture for 706 candidate genes. We identified 16 of 53 participants (30%) with a pathogenic (P) or likely pathogenic (LP) variant that may be related to their hereditary pancreatic cancer predisposition; seven had mutations in genes associated with well-known cancer syndromes (13%) [ATM (2), BRCA2 (3), MSH2 (1), MSH6 (1)]. Many had mutations in Fanconi anemia complex genes [BRCA2 (3 participants), FANCF, FANCM]. Eight participants had rare protein truncating variants of uncertain significance with no other P or LP variants. Earlier age of pancreatic cancer diagnosis (57.5 vs 64.8 years) was indicative of possessing a P or LP variant, as was cancer family history (p values <0.0001). Our multigene panel approach for identifying known cancer predisposing genetic susceptibility in those at risk for hereditary pancreatic cancer may have direct applicability to clinical practice in cases with mutations in actionable genes. Future pancreatic cancer predisposition studies should include evaluation of the Fanconi anemia genes.
Türke C, Horn S, Petto C, et al. Loss of heterozygosity in FANCG, FANCF and BRIP1 from head and neck squamous cell carcinoma of the oral cavity. Int J Oncol. 2017; 50(6):2207-2220 [PubMed] Related Publications
Recent advances have been made in the understanding of Fanconi anemia (FA), a hereditary disease that increases the risk for head and neck squamous cell carcinomas (HNSCC) by 500- to 700-fold. FA patients harbour germline mutations in genes of cellular DNA repair pathways that are assumed to facilitate the accumulation of mutations during HNSCC development. Mutations in these FA genes may also contribute to HNSCC in general. In the present study, we analysed three FA genes; FANCF, FANCG and BRIP1, that are involved in the repair of DNA inter strand cross-links, in HNSCC and their potential role for patient survival. We measured loss of heterozygosity (LOH) mutations at eight microsatellite loci flanking three FA genes in 54 HNSCC of the oral cavity and corresponding blood samples. Survival analyses were carried out using mutational data and clinical variables. LOH was present in 17% (FANCF region), 41% (FANCG region) and 11% (BRIP1 region) of the patients. Kaplan-Meier survival curves and log-rank tests indicated strong clinical predictors (lymph node stages with decreased survival: p=2.69e-12; surgery with improved survival: p=0.0005). LOH in the FANCF region showed a weaker association with decreased overall survival (p=0.006), which however, did not hold in multivariate analyses. LOH may predominantly indicate copy number gains in FANCF and losses in FANCG and BRIP1. Integration of copy number data and gene expression proved difficult as the available sample sets did not overlap. In conclusion, LOH in FA genes appears to be a common feature of HNSCC development seen here in 57% of patients and other mutation types may increase this mutation frequency. We suggest larger patient cohorts would be needed to test the observed association of LOH in FANCF and patient survival comprehensively.
Ding JJ, Wang G, Shi WX, et al. Promoter Hypermethylation of FANCF and Susceptibility and Prognosis of Epithelial Ovarian Cancer. Reprod Sci. 2016; 23(1):24-30 [PubMed] Related Publications
OBJECTIVE: To assess the 5' CpG island methylation of Fanconi anemia, complementation group F (FANCF) gene in epithelial ovarian cancer (EOC) tissues and normal ovarian tissues and to investigate the relationship between FANCF methylation and clinicopathologic features and prognosis of EOC. METHODS: The experiment was performed with 112 EOC tissue samples (case group) and 60 normal ovarian tissues (control group). With methylation-specific polymerase chain reaction (MSP), FANCF methylation status of cases and controls was assessed. And the association between FANCF methylation and the clinicopathological features of EOC was investigated with univariate survival analysis and Cox regression model analysis. RESULTS: The methylation-positive rate of the case group was significantly higher than that of the control group (P = 0.015). The FANCF promoter methylation rates showed significant differences in the comparisons stratified by age, International Federation of Gynecology and Obstetrics (FIGO) staging, histopathological classification, and lymph node metastasis (all P < .05). Univariate survival analysis showed there were significant differences in mean survival time between the groups based on FIGO staging, histopathological classification, lymph node metastasis, and FANCF methylation (all P < .05). Cox regression model analysis suggested that FIGO staging and FANCF methylation were independent risk factors for EOC prognosis. CONCLUSION: CpG island methylation of FANCF gene promoter region is strongly associated with the susceptibility and clinicopathologic features of EOC. The FIGO staging and FANCF methylation are independent risk factors for EOC prognosis.
BACKGROUND: Cisplatin is one of the most commonly used chemotherapy agent for lung cancer. The therapeutic efficacy of cisplatin is limited by the development of resistance. In this study, we test the effect of RNA interference (RNAi) targeting Fanconi anemia (FA)/BRCA pathway upstream genes on the sensitivity of cisplatin-sensitive (A549 and SK-MES-1) and -resistant (A549/DDP) lung cancer cells to cisplatin. RESULT: Using small interfering RNA (siRNA), knockdown of FANCF, FANCL, or FANCD2 inhibited function of the FA/BRCA pathway in A549, A549/DDP and SK-MES-1 cells, and potentiated sensitivity of the three cells to cisplatin. The extent of proliferation inhibition induced by cisplatin after knockdown of FANCF and/or FANCL in A549/DDP cells was significantly greater than in A549 and SK-MES-1 cells, suggesting that depletion of FANCF and/or FANCL can reverse resistance of cisplatin-resistant lung cancer cells to cisplatin. Furthermore, knockdown of FANCL resulted in higher cisplatin sensitivity and dramatically elevated apoptosis rates compared with knockdown of FANCF in A549/DDP cells, indicating that FANCL play an important role in the repair of cisplatin-induced DNA damage. CONCLUSION: Knockdown of FANCF, FANCL, or FANCD2 by RNAi could synergize the effect of cisplatin on suppressing cell proliferation in cisplatin-resistant lung cancer cells through inhibition of FA/BRCA pathway.
Stoepker C, Ameziane N, van der Lelij P, et al. Defects in the Fanconi Anemia Pathway and Chromatid Cohesion in Head and Neck Cancer. Cancer Res. 2015; 75(17):3543-53 [PubMed] Related Publications
Failure to repair DNA damage or defective sister chromatid cohesion, a process essential for correct chromosome segregation, can be causative of chromosomal instability (CIN), which is a hallmark of many types of cancers. We investigated how frequent this occurs in head and neck squamous cell carcinoma (HNSCC) and whether specific mechanisms or genes could be linked to these phenotypes. The genomic instability syndrome Fanconi anemia is caused by mutations in any of at least 16 genes regulating DNA interstrand crosslink (ICL) repair. Since patients with Fanconi anemia have a high risk to develop HNSCC, we investigated whether and to which extent Fanconi anemia pathway inactivation underlies CIN in HNSCC of non-Fanconi anemia individuals. We observed ICL-induced chromosomal breakage in 9 of 17 (53%) HNSCC cell lines derived from patients without Fanconi anemia. In addition, defective sister chromatid cohesion was observed in five HNSCC cell lines. Inactivation of FANCM was responsible for chromosomal breakage in one cell line, whereas in two other cell lines, somatic mutations in PDS5A or STAG2 resulted in inadequate sister chromatid cohesion. In addition, FANCF methylation was found in one cell line by screening an additional panel of 39 HNSCC cell lines. Our data demonstrate that CIN in terms of ICL-induced chromosomal breakage and defective chromatid cohesion is frequently observed in HNSCC. Inactivation of known Fanconi anemia and chromatid cohesion genes does explain CIN in the minority of cases. These findings point to phenotypes that may be highly relevant in treatment response of HNSCC.
Nicchia E, Benedicenti F, De Rocco D, et al. Clinical aspects of Fanconi anemia individuals with the same mutation of FANCF identified by next generation sequencing. Birth Defects Res A Clin Mol Teratol. 2015; 103(12):1003-10 [PubMed] Related Publications
BACKGROUND: Fanconi anemia (FA) is a rare genetic disease characterized by congenital malformations, aplastic anemia and increased risk of developing malignancies. FA is genetically heterogeneous as it is caused by at least 17 different genes. Among these, FANCA, FANCC, and FANCG account for approximately 85% of the patients whereas the remaining genes are mutated in only a small percentage of cases. For this reason, the molecular diagnostic process is complex and not always extended to all the FA genes, preventing the characterization of individuals belonging to rare groups. METHODS: The FA genes were analyzed using a next generation sequencing approach in two unrelated families. RESULTS: The analysis identified the same, c.484_485del, homozygous mutation of FANCF in both families. A careful examination of three electively aborted fetuses in one family and one affected girl in the other indicated an association of the FANCF loss-of-function mutation with a severe phenotype characterized by multiple malformations. CONCLUSION: The systematic use of next generation sequencing will allow the recognition of individuals from rare complementation groups, a better definition of their clinical phenotypes, and consequently, an appropriate genetic counseling.
Yao C, Du W, Chen H, et al. Involvement of Fanconi anemia genes FANCD2 and FANCF in the molecular basis of drug resistance in leukemia. Mol Med Rep. 2015; 11(6):4605-10 [PubMed] Related Publications
The Fanconi anemia (FA)‑associated proteins FANCF and FANCD2 are important components of the FA pathway of DNA crosslink repair. FANCF and FANCD2 have been found to be involved in drug‑resistant multiple myeloma, ovarian cancer, non‑small‑cell lung cancer, and head and neck cancer. However, it is unclear whether these two genes participate in adriamycin (ADR)‑resistant leukemia. Therefore, the aim of the current study was to investigate FANCF and FANCD2 expression in drug‑resistant and drug‑sensitive leukemia cells. Western blot analysis revealed enhanced FANCF expression and monoubiquitination of FANCD2 in ADR‑resistant cells. Additionally, it was observed that drug‑resistant cells had reduced DNA damage compared with drug‑sensitive cells. The results of this study indicate that the FA pathway may confer leukemia resistance to ADR via enhanced DNA interstrand crosslink repair.
Yao C, Du W, Chen H, et al. The Fanconi anemia/BRCA pathway is involved in DNA interstrand cross-link repair of adriamycin-resistant leukemia cells. Leuk Lymphoma. 2015; 56(3):755-62 [PubMed] Related Publications
The Fanconi anemia/BRCA (FA/BRCA) pathway plays a vital role in DNA damage repair induced by DNA cross-linking agents and is closely related to drug response in cancer treatment. Here we demonstrate that the FA/BRCA pathway contributes to acquired drug resistance in adriamycin (ADR)-resistant leukemia cell lines, and disruption of this pathway partially reverses the drug resistance. We observed that ADR-resistant cells have reduced DNA interstrand cross-links (ICL) compared with ADR-sensitive cells. Western blot studies demonstrated enhanced FA protein expression in ADR-resistant cells. Using siRNA to knock down FANCF in K562/R drug-resistant cells showed increases in sensitivity to ADR and ADR-induced DNA damage, and demonstrated a direct relationship between the FA/BRCA pathway and drug sensitivity. Overexpression of FANCF in K562 drug-sensitive cells partially reproduced the drug-resistant phenotype. These results show that the FA/BRCA pathway is involved in acquired ADR resistance of leukemia cells. The FA/BRCA pathway may be a new target to reverse ADR resistance in leukemia treatment.
Zhao L, Li Y, He M, et al. The Fanconi anemia pathway sensitizes to DNA alkylating agents by inducing JNK-p53-dependent mitochondrial apoptosis in breast cancer cells. Int J Oncol. 2014; 45(1):129-38 [PubMed] Related Publications
The Fanconi anemia/BRCA (FA/BRCA) DNA damage repair pathway plays a pivotal role in the cellular response to DNA alkylating agents and greatly influences drug response in cancer treatment. However, the molecular mechanisms underlying the FA/BRCA pathway reversed resistance have received limited attention. In the present study, we investigated the effect of Fanconi anemia complementation group F protein (FANCF), a critical factor of the FA/BRCA pathway, on cancer cell apoptosis induced by DNA alkylating agents such as mitomycin c (MMC). We found that FANCF shRNA potentiated MMC-induced cytotoxicity and apoptosis in MCF-7 and MDA-MB-231 breast cancer cells. At a mechanistic level, FANCF shRNA downregulated the anti-apoptotic protein Bcl-2 and upregulated the pro-apoptotic protein Bax, accompanied by release of cyt-c and smac into the cytosol in MMC-treated cells. Furthermore, activation of caspase-3 and -9, other than caspase-8, cleavage of poly(ADP ribose) polymerase (PARP), and a decrease of mitochondrial membrane potential (MMP) indicated that involvement of the mitochondrial apoptotic pathway in FANCF silencing of MMC-treated breast cancer cells. A decrease in IAP family proteins XIAP and survivin were also observed following FANCF silencing in MMC-treated breast cancer cells. Notably, FANCF shRNA was able to increase p53 levels through activation of the JNK pathway in MMC-treated breast cancer cells. Furthermore, p53 inhibition using pifithrin-α abolished the induction of caspase-3 and PARP by FANCF shRNA and MMC, indicating that MMC-induced apoptosis is substantially enhanced by FANCF shRNA via p53-dependent mechanisms. To our knowledge, we provide new evidence for the potential application of FANCF as a chemosensitizer in breast cancer therapy.
Fanconi anemia complementation group F protein (FANCF) is a key factor, which maintains the function of FA/BRCA, a DNA damage response pathway. However, the functional role of FANCF in breast cancer has not been elucidated. We performed a specific FANCF-shRNA knockdown of endogenous FANCF in vitro. Cell viability was measured with a CCK-8 assay. DNA damage was assessed with an alkaline comet assay. Apoptosis, cell cycle, and drug accumulation were measured by flow cytometry. The expression levels of protein were determined by Western blot using specific antibodies. Based on these results, we used cell migration and invasion assays to demonstrate a crucial role for FANCF in those processes. FANCF shRNA effectively inhibited expression of FANCF. We found that proliferation of FANCF knockdown breast cancer cells (MCF-7 and MDA-MB-435S) was significantly inhibited, with cell cycle arrest in the S phase, induction of apoptosis, and DNA fragmentation. Inhibition of FANCF also resulted in decreased cell migration and invasion. In addition, FANCF knockdown enhanced sensitivity to doxorubicin in breast cancer cells. These results suggest that FANCF may be a potential target for molecular, therapeutic intervention in breast cancer.
Current methods for detecting mutations in Fanconi anemia (FA)-suspected patients are inefficient and often miss mutations. We have applied recent advances in DNA sequencing and genomic capture to the diagnosis of FA. Specifically, we used custom molecular inversion probes or TruSeq-enrichment oligos to capture and sequence FA and related genes, including introns, from 27 samples from the International Fanconi Anemia Registry at The Rockefeller University. DNA sequencing was complemented with custom array comparative genomic hybridization (aCGH) and RNA sequencing (RNA-seq) analysis. aCGH identified deletions/duplications in 4 different FA genes. RNA-seq analysis revealed lack of allele specific expression associated with a deletion and splicing defects caused by missense, synonymous, and deep-in-intron variants. The combination of TruSeq-targeted capture, aCGH, and RNA-seq enabled us to identify the complementation group and biallelic germline mutations in all 27 families: FANCA (7), FANCB (3), FANCC (3), FANCD1 (1), FANCD2 (3), FANCF (2), FANCG (2), FANCI (1), FANCJ (2), and FANCL (3). FANCC mutations are often the cause of FA in patients of Ashkenazi Jewish (AJ) ancestry, and we identified 2 novel FANCC mutations in 2 patients of AJ ancestry. We describe here a strategy for efficient molecular diagnosis of FA.